lambda

1# AWS Lambda
2 
3AWS Lambda runs code without provisioning servers. You pay only for compute time consumed. Lambda automatically scales from a few requests per day to thousands per second.
4 
5## Table of Contents
6 
7- [Core Concepts](#core-concepts)
8- [Common Patterns](#common-patterns)
9- [CLI Reference](#cli-reference)
10- [Best Practices](#best-practices)
11- [Troubleshooting](#troubleshooting)
12- [References](#references)
13 
14## Core Concepts
15 
16### Function
17 
18Your code packaged with configuration. Includes runtime, handler, memory, timeout, and IAM role.
19 
20### Invocation Types
21 
22| Type | Description | Use Case |
23|------|-------------|----------|
24| **Synchronous** | Caller waits for response | API Gateway, direct invoke |
25| **Asynchronous** | Fire and forget | S3, SNS, EventBridge |
26| **Poll-based** | Lambda polls source | SQS, Kinesis, DynamoDB Streams |
27 
28### Execution Environment
29 
30Lambda creates execution environments to run your function. Components:
31- **Cold start**: New environment initialization
32- **Warm start**: Reusing existing environment
33- **Handler**: Entry point function
34- **Context**: Runtime information
35 
36### Layers
37 
38Reusable packages of libraries, dependencies, or custom runtimes (up to 5 per function).
39 
40## Common Patterns
41 
42### Create a Python Function
43 
44**AWS CLI:**
45 
46```bash
47# Create deployment package
48zip function.zip lambda_function.py
49 
50# Create function
51aws lambda create-function \
52  --function-name MyFunction \
53  --runtime python3.12 \
54…